U.S. patent application number 12/670724 was filed with the patent office on 2010-08-19 for method and apparatus for starting a refrigerant system without preheating the oil.
Invention is credited to Sean P. Breen, Peter S. Matteson.
Application Number | 20100205966 12/670724 |
Document ID | / |
Family ID | 40304576 |
Filed Date | 2010-08-19 |
United States Patent
Application |
20100205966 |
Kind Code |
A1 |
Matteson; Peter S. ; et
al. |
August 19, 2010 |
METHOD AND APPARATUS FOR STARTING A REFRIGERANT SYSTEM WITHOUT
PREHEATING THE OIL
Abstract
A rankine cycle system, which includes a turbine for driving a
generator by way of a gearbox having an oil sump, is adapted to
have the oil heated relatively quickly by causing a mixture of hot
refrigerant gases from the evaporator and the oil from the low
portion of the turbine to be mixed in an eductor and flow to the
oil sump for heating the oil.
Inventors: |
Matteson; Peter S.; (South
Windsor, CT) ; Breen; Sean P.; (Holyoke, MA) |
Correspondence
Address: |
MARJAMA MULDOON BLASIAK & SULLIVAN LLP
250 SOUTH CLINTON STREET, SUITE 300
SYRACUSE
NY
13202
US
|
Family ID: |
40304576 |
Appl. No.: |
12/670724 |
Filed: |
July 27, 2007 |
PCT Filed: |
July 27, 2007 |
PCT NO: |
PCT/US07/16945 |
371 Date: |
January 26, 2010 |
Current U.S.
Class: |
60/646 ;
60/671 |
Current CPC
Class: |
F01K 13/02 20130101;
F02C 1/05 20130101; F02C 7/16 20130101; F01D 25/18 20130101; F01K
25/10 20130101 |
Class at
Publication: |
60/646 ;
60/671 |
International
Class: |
F01K 13/02 20060101
F01K013/02; F01K 25/00 20060101 F01K025/00 |
Claims
1. A method of starting an organic rankine cycle system of the type
having an evaporator and a turbine driven generator with an oil
sump, comprising the steps of: providing an eductor with primary
and secondary flow inlets; fluidly connecting said primary flow
inlet to an outlet of said evaporator; fluidly connecting said
secondary flow inlet to a lower portion of said turbine; and
operating said eductor to pump a mixture of oil and refrigerant
vapor to the oil sump to thereby heat the oil therein.
2. A method as set forth in claim 1 and including the step of, when
the oil reaches a predetermined temperature level, connecting the
flow of refrigerant vapor from the evaporator to the turbine.
3. A method as set forth in claim 2 and including the preliminary
step of pumping the refrigerant through the system but bypassing
the turbine.
4. A method as set forth in claim 3 including the preliminary step
of applying heat to the evaporator.
5. A method as set forth in claim 1 wherein said system includes an
inlet valve upstream of said turbine and wherein said fluid
connection is between said evaporator and said inlet valve.
6. A rankine cycle system of the type having in serial flow
relationship a pump, an evaporator, a turbine and a condenser, with
the turbine being applied to drive a generator through a gearbox
having an oil sump, comprising; an eductor with primary and
secondary flow inlets; fluid connection between said secondary flow
inlet and a lower portion of said turbine for conducting the flow
of oil therein; fluid connection between an outlet of said
evaporator and said primary flow inlet for conducting the flow of
hot refrigerant gas therein; and fluid connection between an outlet
of said eductor and said oil sump for conducting the flow of a
mixture of oil and hot refrigerant gases therein.
7. The apparatus as set forth in claim 6 and including a turbine
inlet valve upstream of said turbine and downstream from said
evaporator, wherein said fluid connection from said evaporator is
located upstream of said turbine inlet valve.
Description
TECHNICAL FIELD
[0001] This disclosure relates generally to organic rankine cycle
systems and, more particularly, to a method and apparatus for
starting such a system without preheating the lubricant.
BACKGROUND OF THE DISCLOSURE
[0002] The well known closed rankine cycle comprises a boiler or
evaporator for the evaporation of a motive fluid, a turbine fed
with vapor from the boiler to drive the generator or other load, a
condenser for condensing the exhaust vapors from the turbine, and
the apparatus, such as a pump, for cycling the condensed fluid to
the boiler. Such a system is shown and described in U.S. Pat. No.
3,393,515.
[0003] With the advent of the energy crisis, and the need to
conserve and to more effectively use the available energies,
rankine cycle systems have been used to capture the so called
"waste heat" or the energy from naturally occurring sources such as
methane gas flares or geo-thermal heat sources. A turbine as
applied for this purpose is shown and described in U.S. Pat. No.
7,174,716 assigned to the assignee of the present invention.
[0004] In order to start such a refrigerant system, the oil used to
lubricate the bearing of the turbine must be heated to bring the
temperature above the point where refrigerant will condense and
displace the oil. This has traditionally been accomplished by using
a heater which is effective in maintaining the temperature once it
has been achieved but takes a relatively long time to do so. It is
therefore desirable to substantially reduce the time for starting
up such an organic rankine cycle system and possibly eliminate the
need for an oil heater.
DISCLOSURE
[0005] Briefly, in accordance with one aspect of the disclosure,
hot refrigerant vapor is drawn from a point downstream of the
evaporator and upstream of the turbine inlet valve and routed to
the eductor to draw oil from the turbine suction housing and pump a
mixture of refrigerant vapor and oil to the oil sump to thereby
heat the oil in the sump.
[0006] In the drawings as hereinafter described, a preferred
embodiment is depicted; however, various other modifications and
alternate constructions can be made thereto without departing from
the spirit and scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic illustration of an organic rankine
cycle system in accordance with the prior art.
[0008] FIG. 2 is a schematic illustration of the turbine and
generator portion thereof with the flow of oil indicated in
accordance with the prior art.
[0009] FIG. 3 is a schematic illustration thereof in accordance
with the present disclosure.
[0010] FIG. 4 is a flow diagram of the method in accordance with
the present disclosure.
DESCRIPTION
[0011] Shown in FIG. 1 is an organic rankine cycle system of the
type which is typically used for the purpose of using waste heat or
natural occurring heat sources to generate electricity. It
includes, in serial flow relationship, a pump 11, an evaporator 12,
a turbine 13 and a condenser 14. The working fluid can be any
suitable refrigerant such as R-245fa.
[0012] The heat source for heating the boiler or evaporator 12 can
be any suitable source such as the exhaust of a gas turbine engine,
methane gas flares, or a geo-thermal heat source providing hot
water to the evaporator 12 as shown.
[0013] The turbine 13 is mechanically connected by way of a gear
box (not shown) to a generator 16 for generating electricity. A
bypass orifice 18 is provided to bypass the turbine 13 during start
up of the system so that the temperature and pressure of the
refrigerant can first rise to the desired level to ensure proper
operation of the turbine 13.
[0014] The condenser 14 can be either air cooled or water cooled by
way of a heat sink 19 as shown.
[0015] A portion of the organic rankine cycle system is shown in
FIG. 3 including the evaporator 12 and the turbine 13. The turbine
13 includes a high pressure volute 21, a suction housing 22 and an
impeller 23 and may be of the type shown and described in U.S. Pat.
No. 7,174,716 assigned to the assignee of the present application.
A turbine inlet valve 24 fluidly interconnects the evaporator 12 to
the high pressure volute 21.
[0016] In operation, refrigerant vapor is passed from the
evaporator 12 through the turbine inlet valve 24 to the high
pressure volute 21 and then passes through nozzles 26 to impart
motive force to the impeller 23 to drive a shaft 27 in a gear box
28. The drive shaft 27 is then connected by gears 29 to drive a
generator 31. The gear box 28 includes an oil sump 32 and an oil
pump 33 to pump oil up to the gears 29 and the bearings 34 prior to
being passed to the oil cooler (not shown).
[0017] Within the refrigerant flow circuit, oil tends to become
emulsified within the refrigerant to provide a mixture of the two
substances. Thus, within the suction housing 22, the oil tends to
separate from the vapor and collect in the bottom portion of the
suction housing 22 as shown. It is thus desirable to return this
oil to the oil sump 32. This is accomplished by way of an eductor
36 having a primary flow inlet 37 and a secondary flow inlet 38.
The primary flow inlet 37 is fluidly connected by line 39 to the
high pressure volute 21, and the secondary flow inlet 38 is fluidly
connected by line 41 to the lower portion of the suction housing 22
as shown.
[0018] In operation, the high pressure refrigerant vapor from the
high pressure volute 21 passes along line 39 to the primary flow
inlet 37 of the eductor 36 to thereby cause the secondary flow of
oil from the suction housing 22 to flow through line 41 and into
the secondary flow inlet 38, with the mixture then flowing along
line 42 to the oil sump 32. The refrigerant vapor then rises in the
gearbox 28 and is caused by pressure gradient to move to the
suction housing 22 so as to flow from the gearbox 28 to the suction
housing along line 45.
[0019] A mixture of refrigerant and oil also exists in the
evaporator 12 with the oil passing along line 49 to the suction
housing 22.
[0020] Traditionally, at system start up the oil in the sump 32 is
cold and therefore and not in a suitable condition for proper
circulation within the system. Accordingly, this problem has
traditionally been addressed by the use of heater 51 which is
placed within the oil sump 32 as shown. In one form, the heater 51
is an electrical heater which is capable of heating the oil in a
relatively short period of time. However it is desirable to
eliminate the waiting period that is necessary for this function
and, if possible, eliminate the heater 51 altogether.
[0021] Referring now to FIG. 3, it will be seen that the high
pressure volute 21 is no longer being applied to the primary flow
inlet 37. Rather, hot refrigerant vapor is taken from line 52 at a
point downstream of the evaporator 12 but upstream of the turbine
inlet valve 24. This hot refrigerant vapor is routed along line 53
to the primary flow inlet 37. As before, the oil is drawn from the
suction housing 22 and flows along line 41 to the secondary flow
inlet 38. However, because of the hot refrigerant gas, the mixture
of oil and refrigerant that flows along line 42 to the oil sump 32
is substantially increased in temperature (i.e. in the range of -).
Accordingly, oil in the sump 32 is heated much more quickly then in
the case of the prior art, thereby allowing a system to be started
much earlier than before. The oil heater 51 of the prior art can
therefore be eliminated.
[0022] Considering now the manner in which the system is started,
the sequence of events is shown in FIG. 4. First, the pump 11 is
turned on to circulate refrigerant through the system as shown in
block 54. Then the geothermal heat source 16 is applied to heat the
evaporator 12 as shown in block 55. The oil temperature alarms can
be disabled as shown in block 56 since, even though the oil is cold
at this point, the present system allows for start up of the system
with these features as described hereinabove. Since the system must
be in operation for a period of time before the vapor is
superheated for proper operation of the turbine 13, the bypass
orifice 18 is opened to allow circulation of the refrigerant
through the system but around the turbine 13 as shown in block
57.
[0023] The oil pump 33 is then turned on as indicated at block 58
to circulate the oil within the system (i.e. within the gearbox 28
and the generator 31). The high temperature refrigerant leaving the
evaporator 12 goes through the eductor 36 heating the oil being
pumped from the suction housing 22 and then flowing to the sump 32
to heat the oil there as indicated at block 59. Once the oil
reaches an appropriate temperature for the system to properly
operate, the power plant is allowed to resume normal operation and
switch to power generation mode as shown in block 61.
[0024] While the present invention has been particularly shown and
described with reference to the preferred mode as illustrated in
the drawing, it will be understood by one skilled in the art that
various changes in detail may be effected therein without departing
from the spirit and scope of the invention as defined by the
claims.
* * * * *